In several industries such as the construction industry or industries where pipelines are used to transport fluid pressurized fluids, very large nuts and bolts are used to fasten jointed pipe members together. For example, large pipes are connected by large pipe flanges and pipe, structural members may also be tightened by the use of large nuts and bolts as well as other structural members, wind generator tower sections, utility poles and a myriad of other applications may use very large nuts and bolts.
Large nuts and bolts used in these industrial applications require high amounts of torque to be properly tightened. As result, large amounts of torque is also required to loosen these large fasteners. Because of the high torque requirements needed to tighten or loosen these large fasteners it would be impractical to use mechanical torque wrenches. As such, the industry has turned to the use of hydraulic torque wrenches which are capable of generating thousands of foot-pounds of torque. These torque wrenches may be driven by a hydraulic pump capable of delivering about 10,000 PSI to the hydraulic torque wrench. These torque wrenches often incorporate a double acting hydraulic cylinder to push a rotary ratchet to apply the torque.
A commonly encountered problem with many hydraulic pumps used to drive hydraulic torque wrenches is that a hand pendant is used by the operator to extend and retract the hydraulic cylinder with in the torque wrench. An operator must actuate an actuator on the hand pendant to extend and again actuate the actuator to retract the hydraulic cylinder within the torque wrench. This requires many repeated operations of actuating the actuator for each faster. The operator's hand may become quickly fatigued. This may become a problem particularly in instances where there are many fasteners that need to be tightened or loosened. Furthermore, requiring repeated operations of actuating the actuator on the hand pendant is slow and not efficient.
Accordingly, it is desirable to provide a method and apparatus that allows a fastener to have an appropriate amount of torque applied to it while at the same time not requiring an operator to constantly actuate an actuator in order to provide the appropriate amount of torque. Further, it may be useful to have a pump that will automatically cycle the torque wrench through extending and retracting the hydraulic cylinder contained within the torque wrench while the operator merely actuates a button or other actuator a single time for each faster. It may also be desirable for the pump to not only automatically cycle the wrench to completely tighten or loosen the faster but also shut down when a proper torque is achieved.